Container

ABSTRACT

A container comprising a sidewall and an endwall connected by a heat sealed joint. The endwall has, in an operable orientation, a major upper surface, an endless, upwardly opening, peripheral channel and a heat sealable, fluid barrier, surface layer adhered to the major upper surface of the endwall. The sidewall has a heat sealable, fluid barrier, surface layer adhered to its inner and outer surfaces. The end of the sidewall is engaged and crimped within the endwall channel with the surface layers of the sidewall heat sealed to the surface layer of the endwall to form a sealed, mechanically rigid joint.

(e) BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to containers for containing fluid materials, such liquids, powders and granular materials and potentially fluid materials, such as ice cream, and more specifically relates to the structure and method of joining and sealing a container endwall, such as its bottom, to its sidewall.

[0003] 2. Description of the Related Art

[0004] Containers for fluids often are made with a bottom endwall, which is attached to a surrounding sidewall of the container. The prior art has disclosed the use of fluid barriers, such as polyethylene, as a film coated on fluid pervious wall material, such as paperboard, in order to prevent absorption or leakage of the fluid. Bulk ice cream is typically packaged in a three gallon container having a cylindrical sidewall joined to a circular endwall. Although ice cream is frozen solid in its normal state, when it is warmed during use, some will become liquid. Ice cream or any other substance which is, or may become, liquid must be contained in a way in which leakage will not occur.

[0005] One part of such a container which is particularly subject to leakage is the joint between the sidewall and the endwall. The prior art has provided a variety of ways of sealing the joint between the sidewall and the endwall. Some use a metal ring or an entirely metal endwall, such as shown in U.S. Pat. No. 2,303,322, in order to obtain a strong, durable crimp between the endwall and sidewall. However, metal rings may cause contamination of the product held within the container, if the product is for human consumption. Metal endwalls or rings also may have exposed sharp edges which can cause injury or damage and also make it more difficult to inspect a contained product with a security device such as a metal detector or x-ray device. These difficulties can increase the cost of and/or delay the shipping or receiving of products in this type of container. Additionally, a metal ring presents an additional component to be assembled onto the container and therefore increases the cost of assembly for companies which assemble and fill containers.

[0006] Other prior art containers use a separate or additional means for sealing the joint between the sidewall and the endwall. Some, such as shown in U.S. Pat. Nos. 2,303,322 and 4,117,971 add a fillet or seal by filling the interior of the joint with an additional sealing material. This, however, requires the additional manufacturing step, and its added expense, of applying the sealing material, usually after the sidewall is joined to the endwall.

[0007] Still other prior art, such as U.S. Pat. No. 4,556,166, adds a separate, additional sealing disk to seal the endwall to the sidewall. Although effective, this also requires an additional component to ship and handle and an additional manufacturing step to assemble the container.

[0008] Not only is it important to construct a container so that it is entirely fluid impervious, but it is also important that the fluid impervious characteristics be maintained after the container is subjected to the mechanical stress of retaining the contents and of being subjected to handling during filling, shipping and use. Thus, the mechanical strength of the joint between the sidewall and endwall should be sufficiently strong that the fluid impervious seal will not become broken.

[0009] As with most containers, it is also desirable that the cost of manufacture be minimized so long as the above characteristics are also maintained. Therefore, it is desirable that the number of component structures to be assembled and the manipulative operations required to assemble the container be minimized.

[0010] It is, therefore, an object of the invention to provide a container structure that requires no manipulative step of forming the sidewall to fit into the endwall, requires no separate component part for sealing the sidewall to the endwall, requires no metal components, and that still provides both a very good seal and a strong mechanical connection between the sidewall and the endwall.

[0011] A further object of the invention is to provide a container structure which permits a minimum number of component parts to be shipped to the manufacturer of the product to be filled into the container, permits those parts to be shipped in a flat, nested configuration in order to ship and store them in a compact form thereby minimizing shipping and storage costs and permits the parts to be assembled with a minimum of manipulative operations in order to minimize costs.

(f) BRIEF SUMMARY OF THE INVENTION

[0012] The invention is a container comprising a sidewall and an endwall connected by a heat sealed joint. The endwall has, in an operable orientation, a major upper surface, an endless, upwardly opening, peripheral channel for receiving and engaging the sidewall and a heat sealable, fluid barrier, surface layer adhered to the major upper surface of the endwall. The sidewall has an inner surface, an outer surface and a heat sealable, fluid barrier, surface layer adhered to at least one of said sidewall surfaces. The end of the sidewall is engaged within the endwall channel with the surface layer or layers of the sidewall heat sealed to the surface layer of the endwall.

(g) BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0013]FIG. 1 is a view in side elevation of a container embodying the present invention.

[0014]FIG. 2 is view in vertical section taken substantially along the line 2-2 of FIG. 1 illustrating the sidewall and end wall of the container of FIG. 1 before assembly.

[0015]FIG. 3 is view in vertical section taken substantially along the line 2-2 of FIG. 1 illustrating the sidewall and end wall of the container of FIG. 1 after assembly and heat sealing them together.

[0016]FIG. 4 is an enlarged view showing in detail the unassembled joint components of FIG. 2.

[0017]FIG. 5 is an enlarged view showing in detail the assembled joint components of FIG. 3.

[0018]FIG. 6 is a view in vertical section illustrating the preferred manner of crimping and heat sealing the endwall to the sidewall of a container embodying the invention.

[0019]FIGS. 7 through 9 are views in vertical section sequentially illustrating the assembly, crimping and heat sealing steps of the invention.

[0020] In describing the preferred embodiment of the invention, which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents, which operate in a similar manner to accomplish a similar purpose.

(h) DETAILED DESCRIPTION OF THE INVENTION

[0021]FIG. 1 illustrates a container 10, which is a cylindrical canister of the type commonly used for containing ice cream. The container 10 has a cylindrical sidewall 12 and a circular endwall 14 enclosing its bottom end. A rim or ring 16, though not necessary, may be frictionally engaged upon the top edge of the sidewall 12 to receive a lid 18. FIG. 2 illustrates the sidewall 12 and endwall 14 prior to assembly and FIG. 4 illustrates a segment of those two components in enlarged detail.

[0022] In its operable orientation when operating as a bottom, the endwall 14 has a major upper surface 20 and an endless, upwardly opening, peripheral channel 22. A heat sealable, fluid barrier, surface layer 24 is adhered to the major upper surface 20 of the endwall 14. Adhered, as used in the context of this description, is directed to a film layer bonded to the paperboard of a principal wall material, such as paperboard, regardless of how the fluid impervious layer was formed there, for example by extrusion, spraying or otherwise depositing a fluid impervious material to form the layer in situ or by bonding a preformed film to the surface of the sheet.

[0023] In the preferred embodiment, as an example of the invention, the endwall 14 is formed of paperboard, and particularly 0.028″ caliper CNK. The fluid barrier surface layer 24 on the upper surface 20 is preferably an extrusion coated layer of 0.75 mil, low density polyethylene. Preferably the opposite surface of the endwall 14 is coated with an aqueous Michelman coating PK910. This coating is applied to prevent moisture penetration and to aid in the thermoforming process used to form the channel. The upwardly opening peripheral channel 22 is thermoformed by pressing an initially circular disc around its edge, to form a channel having a lengthwise contour which follows the contour of the end of the later inserted sidewall. As will be seen, this permits the end edge of the sidewall to extend into the channel and ultimately be engaged by it. The invention is not limited to paperboard, but may be applied to other materials, which have a heat sealable layer.

[0024] The sidewall 12 has a heat sealable, fluid barrier, surface layer 26 adhered to the inner surface of the sidewall 12, and a similar surface layer 28 adhered or coated on the outer surface of the sidewall 12. Although it is only necessary that the fluid barrier surface layer be formed on only one of the surfaces of the sidewall, preferably the interior surface, most preferably the fluid barrier surface layer is formed on the interior and exterior surfaces of the sidewall in order to maximize the moisture resistance of the paperboard sidewall 12, maximize the seal between the endwall 14 and the sidewall 12 and maximize the mechanical strength of the connection of the endwall 14 to the sidewall 12. The surface layers 26 and 28 on the sidewall are preferably formed in the same manner and of the same material as the surface layer 24 on the endwall 14.

[0025] The container components illustrated in FIGS. 2 and 4 are assembled into the container illustrated in FIG. 3 having the detailed structure illustrated in FIG. 5. The sidewall 12 is moved into engagement in the peripheral channel 22 formed around the endwall 14. The peripheral channel 22 is then crimped against the lower rim of the cylindrical sidewall 12 and the engaged lower rim and channel are heated to heat seal together the fluid barrier, surface layer 24 of the end wall 14 and the fluid barrier, surface layers 26 and 28 of the sidewall 12, as illustrated in FIG. 5. Because the single fluid barrier layer formed on the endwall is heat sealed to both of the fluid barrier layers on the sidewall, there is a double seal at this joint and both also contribute to the mechanical strength and durability of the joint.

[0026] Containers embodying the invention are not limited to cylindrical canisters. Containers may be made having a rectangular, oval or other geometrical configurations. For example, an endwall may be formed in an oval or rectangular polygon with a channel around its peripheral edge to receive a sidewall having an end with a cross-sectional shape contoured and sized to matingly engage within the channel.

[0027] As another alternative, it is unnecessary to provide an interior or exterior surface layer upon the entire surface of the sidewall for purposes of the present invention. For example, for purposes of the invention, the heat sealable, fluid barrier, surface layer could be applied only around the lower surface area of the sidewall, such as in a peripheral annular ring, where it can engage the surface layer formed on the surface of the endwall within the channel. However, although this can be done to provide the joint seal, mechanical strength and other advantages of the present invention, it is not preferred because the surface layer is also desired over the entire inner surface of the sidewall, so that it can provide its conventional, prior art fluid barrier characteristic to the entire container. In a like manner, the surface layer can be adhered on the endwall only within the endless channel in order to provide the advantages of the invention, but this too is not desired because it is preferable that the entire endwall surface have a fluid barrier to accomplish its conventional prior art purpose.

[0028] FIGS. 6-9 illustrate the preferred method for assembling the endwall to the sidewall in order to form a container embodying the present invention. Preferably they are assembled while in an inverted orientation by supporting the sidewall 12 within a circular groove 40, formed in a support platform 42. A mandrel 56 is supported on the support platform 42 and has a shape and size to conform to and support the interior of the finished container. A first die 44 is shaped to engage an inwardly facing wall 46 on the exterior of the channel 22 formed around the endwall 14. A mating die 48 supports the die 44 by means of springs 50. The mating die 48 has a surface 52 formed to engage an outwardly facing surface 54 of exterior of the channel 22.

[0029] The endwall 14 is assembled to the sidewall 12 by first positioning the endwall 14 to sit upon the sidewall 12 so that the sidewall 12 is inserted into the channel 22. The top of a mandrel 56 supports the endwall 14 when the channel 22 has been brought into engagement with the sidewall 12. The dies 44 and 48 are then lowered. The die 44 first engages the inwardly facing wall 46 on the exterior of the channel 22 as illustrated in FIG. 6. This sequence is illustrated in going from FIG. 7 to FIG. 8, in which the sidewall 12 has been brought into engagement with the channel 22 and the die 44 engages the end wall 14.

[0030] The endwall channel 22 is then crimped against the sidewall 12 to form a joint, as illustrated in FIG. 9. This is accomplished by lowering the die 48 so that the channel 22 is compressively wedged against the sidewall by the dies 44 and 48 to affect the crimping. Heat is applied to the exterior surfaces of the channel 22 so that the heat sealable surface layers or films deposited on the engaging surfaces within the joint become heat sealed, i.e. welded together. This may be accomplished with conventional electrical resistance heaters, mounted in the dies 44 and 48 in the vicinity of the joint, while the joint is being crimped and compressibly wedged between the dies 44 and 48. The heat is conducted from the dies to the engaged heat sealable materials. The heat sealable layers become softened and melted, in the manner known to those skilled in the art, so that they are bonded and/or flow together.

[0031] From the above description, it is apparent that a container embodying the present invention is easier to assemble because it only requires one assembly step on the assembly machine instead of the two steps for containers which utilize metal rings. The structure of the invention also does not require any forming of the sidewall, such as formation of a flange, channel or lip, to permit it to be attached too the bottom. Instead the simple end edge of the sidewall is inserted into and engaged with the channel of the endwall.

[0032] The container parts can be shipped economically in bulk to the end user, who will package a product in the container, because the component parts can be stacked in a relatively flat configuration. Therefore these parts can be compactly packaged for shipment to the filler, who then assembles them as they are needed to package the filler's product. The sidewall components can be shipped and stored as a stack of planar sheets and are bent or contoured into a cylindrical or other sidewall geometrical shape when being assembled for filling. The endwall components, with the channel already formed, are easily shipped and stored as a nested stack.

[0033] Because of the strength of the heat sealed joint, the invention is also able to make the use of metal rings or other metal components unnecessary, thereby avoiding the problems described above.

[0034] While certain preferred embodiments of the present invention have been disclosed in detail, it is to be understood that various modifications may be adopted without departing from the spirit of the invention or scope of the following claims. 

1. A container comprising: a) an endwall having, in an operable orientation, a major upper surface, an endless, upwardly opening, peripheral channel and a heat sealable, fluid barrier, surface layer adhered to the major upper surface of the endwall; and b) a sidewall, having an inner surface, an outer surface, a heat sealable, fluid barrier, surface layer adhered to at least one of said sidewall surfaces, an end of the sidewall being engaged within the channel with the surface layer of the sidewall heat sealed to the surface layer of the endwall.
 2. The container in accordance with claim 1 wherein the cross sectional configuration of the sidewall and the peripheral configuration of the endwall are identical geometrical shapes selected from the group consisting of oval, square, rectangular, triangular and trapezoidal.
 3. The container in accordance with claim 1 wherein the sidewall has a circular cross section and the endwall is circular.
 4. The container in accordance with claim 1, wherein the endwall is a paperboard sheet material.
 5. The container in accordance with claim 3, wherein the sidewall is a paperboard sheet material.
 6. The container in accordance with claim 1, wherein the inner surface of the sidewall has a heat sealable surface layer.
 7. The container in accordance with claim 1, wherein the outer surface of the sidewall has a heat sealable surface layer.
 8. The container in accordance with claim 1, wherein both the outer surface and the inner surface of the sidewall have a heat sealable surface layer heat sealed to the endwall surface layer.
 9. The container in accordance with claim 1, wherein the heat sealable surface layer is polyethylene.
 10. The container in accordance with claim 1, wherein the endwall channel is crimped to seat the heat sealable surface layer at the channel against the sidewall.
 11. The container in accordance with claim 10, wherein the endwall and the sidewall are a paperboard sheet material, wherein both the outer surface and the inner surface of the sidewall have a heat sealable surface layer heat sealed to the endwall surface layer.
 12. The container in accordance with claim 11, wherein the surface layers are polyethylene.
 13. The container in accordance with claim 12, wherein the sidewall is cylindrical and the endwall is circular.
 14. A method for forming a container, the method comprising: a) forming an endless, peripheral channel in an endwall constructed of a sheet material having, in an operable orientation, a major upper surface and a heat sealable, fluid barrier, surface layer adhered to the major upper surface and extending into the channel; b) inserting a sidewall into engagement in the channel, the sidewall having an inner surface, an outer surface, and a heat sealable, fluid barrier, surface layer adhered to at least one of said surfaces; c) crimping the endwall channel against the sidewall to form a joint; and d) heating said joint to heat seal the heat sealable layers of the endwall and the sidewall at the joint.
 15. The method for forming a container in accordance with claim 14, wherein the crimping and heating steps comprise: (a) heating a pair of mating male and female dies, one die formed to engage an inwardly facing wall of the channel and the other die formed to engage an outwardly facing wall of the channel; and (b) compressibly wedging the channel against the sidewall between the dies to effect crimping and to transfer heat to the joint.
 16. The method for forming a container in accordance with claim 15 further comprising supporting the endwall on a mandrel when the channel is engaged with the sidewall. 